Sewing machine with loop support



United States Patent Manfred Finster inventor Karlsruhe, Waldstadt, Germany Appl. No. 783,872 Filed Dec. 16, 1968 Patented Oct. 13, 1970 Assignee G. M. Pfaff AG.

Kaiserslautern, Germany Priority Dec. 21, 1967 Germany SEWING MACHINE WITH LOOP SUPPORT 3 Claims, 2 Drawing Figs.

U.S. Cl 112/227 Int. C1 D05b 55/06 Field of Search 1 12/228, 231, 227, 260

References Cited UNITED STATES PATENTS 1,388,943 8/192] Gatchell 112/227 3,107,639 10/1963 Basile 112/227 3,125,049 3/1964 Redman 112/23lX 3,199,480 8/1965 Covert et al. 112/231X FOREIGN PATENTS 1,443,760 5/1966 France 112/228 Primary ExaminerAlfred'R. Guest All0rney-R0bert H. Jacob ABSTRACT: In a sewing machine with a needle carrying the thread and having a looper that cooperates with the needle for stitch formation and a supporting wall located laterally of the path of the needle for the leg of the thread that leads to the thread supply, which supporting wall 10, 10a is provided with a plurality of grooves 12, 12a that extend parallel to the path of movement of the needle 2.

Patented Ocf. ,13, 1970 1 SEWING MACHINE WITH LOOP SUPPORT BACKGROUND OF THE INVENTION The present invention relates to sewing machines. More in particular, the invention is concerned with a sewing machine having a needle carrying a needle thread and a looper cooperating with the needle for stitch formation, as well as a supporting wall provided laterally of the path of the needle for the leg of the needle thread that guides the thread supply.

For the purpose of forming a better needle thread loop it has already been proposed to provide a supporting wall for the leg of the thread which leads to the thread supply. The supporting wall in that connection may, according to former proposals, be arranged at the looper as well as also below the stitch plate of the sewing machine. Such a supporting wall effects an increase of the thread loop on the side of the needle which is remote from this wall. To be sure, this measure provides for improved loop formation, however, due to the lack of lateral guidance of the thread through the work blank, it is not possible to obtain a stable loop support that makes possible unobjectionable seizing of the thread loop by the looper point also when very wide meshed material is being sewed or when the needle stitches past the work blank.

SUMMARY OF THE INVENTION It is an object of the invention to form the wall provided for the support of the loop in a manner that sufficient stabilization is insured for reliable stitch formation under all sewing conditions for the needle thread loop that is being formed.

In accordance with the invention, this is accomplished in that the support wall is provided with a plurality of grooves that extend parallel to the path of movement of the needle.

In zig-zag sewing machines the grooves extend suitably over the entire width of the magnitude of the deflections of the needle.

BRIEF DESCRIPTION OF THE DRAWINGS Further features and details of the invention will become apparent from the following description of an embodiment illustrated in the drawings, in which:

FIG. 1 is a perspective illustration of a part of a sewing machine having a rotary double stitch looper, of the needle and of a part of the stitch plate, and

FIG. 2 is a section along line II-II of FIG. 1 in a position where the point of the looper enters the loop of the thread,

DESCRIPTION OF THE INVENTION The needle 2 which carries the needle thread 1 cooperates with the rotary looper 3 which is disposed below the stitch plate 6 that is provided with passage slots 4 for the material feed dog which is not shown and with a stitch slot 5 extending transversely thereto. a

The rotary looper 3 contains the bobbin casing 7 which is at stand still during the operation of the machine. It is furthermore equipped with the bottom thread bobbin 8. The passage aperture 9 for the needle 2 is joined by the supporting wall I0. The supporting wall 10 which is located on that side of the path of the needle 2 which is opposite the path of the looper point 1.1 is provided with a plurality of grooves 12 that extend parallel to the path of movement of the needle 2. When a rotary looper 3 is used on zig-zag sewing machines, the grooves suitably extend over the entire width of the maximum deflection of the needle 2.

As the needle 2 moves downward it pierces the material 14 disposed between the presser foot 13 and the stitch plate 6 and moves the leg of the thread 15 of the needle thread I which leads to the thread supply, as well as also the leg of the thread 16 that leads to the work blank, under the stitch plate 6.

The supporting wall 10 in this connection prevents the formation of a thread loop on the side of the leg of the thread 15 as the needle 2 moves downwardly, while due to the placin of the thread 15 into one of the grooves 12 lateral dropping o of this thread leg is prevented. Simultaneously this measure advantageously affects the formation of a thread loop which is sufficient for the safe entrance of the looper point 11 of the thread leg 16 that leads to the work blank 14.

Besides the arrangement of the grooves 12 in the supporting wall 10 of the bobbing housing 7 corresponding grooves 12a may also be provided in a block 17 that is secured below the stitch plate 6, particularly in a supporting wall of the block. 17 that projects into the range of the stitch hole slot 5.

I claim:

I. A thread loop support in a zig-zag sewing machine having a stitch plate having a stitch slot, a needle supported above 'said stitch plate in alignment with said slot, a looper mounted on a horizontal axis below said stitch plate, a bobbin housing in said looper and a bobbin in said housing, said looper cooperating with said needle to form stitches, said thread loop support comprising a supporting wall for the leg of thread fed from a supply by said needle said wall being mounted below said stitch plate and disposed laterally of said stitch slot, and a plurality of grooves in one side of said supporting wall extending parallel to said needle and its path of movement and parallel to each other.

2. A thread loop support in accordance with claim 1 wherein said grooves extend over the entire width of the lateral deflection of the needle. 

